Billet grinder apparatus, particularly for contour grinding of pipe

ABSTRACT

A billet grinding apparatus with open loop control, in which the grinding wheel head mounted on a pivotable boom is capable of following with substantially constant force a contour work surface varying rapidly in a vertical direction, presented to the wheel by the workpiece, particularly that presented by a rapidly rotating pipe having appreciable eccentricity and camber. The improvement consists in combining a boom assembly with minimal rotational inertia, a characteristic obtained by mounting the large mass, driving motor off the boom, using no counterweight for the grinding head and boom, and driving the grinding head through an intermediate drive shaft coaxial with the boom pivot; actuators having minimal frictional characteristics, a low ratio of incremental volume to total volume, and a location such that their force is applied to the boom close to the pivotal axis thus reducing the amplitude of their motion; and a master cylinder for raising the grinding head from the workpiece in case of an emergency such as loss of air pressure, but connected through a lost-motion connection permitting the boom to operate during grinding essentially free of the connection.

United States Patent 1191 Durst et al.

[4;] Oct. 1, 1974 BILLET GRINDER APPARATUS,

PARTICULARLY FOR CONTOUR GRINDING OF PIPE [75] Inventors: Fred L. Durst,Palos Heights;

Rudolph J. Zastera, Glen Ellyn, both of Ill.

[73] Assignee: Pettibone Corporation, Chicago, Ill.

[22] Filed: Dec. 21, 1972 [21] Appl. No.: 315,641

[52] US. Cl. 51/79, 51/99 [51] Int. Cl B24b 5/18 [58] Field of Search51/99, 103 R, 103 TF, 39,

[56] References Cited UNITED STATES PATENTS 2,418,737 4/1947 Talboys51/99 2,694,274 11/1954 McGibbon 2,963,832 12/1960 Ohringer 3,143,3058/1964 Hess et al. 51/99 Primary ExaminerAl Lawrence Smith AssistantExaminer-Robert C. Watson Attorney, Agent, or Firm-Frank B. Hall 5 7ABSTRACT A billet grinding apparatus with open loop control, in whichthe grinding wheel head mounted on a pivotable boom is capable offollowing with substantially constant force a contour work surfacevarying rapidly in a vertical direction, presented to the wheel by theworkpiece, particularly that presented by a rapidly rotating pipe havingappreciable eccentricity and camber. The improvement consists incombining a boom assembly with minimal rotationalinertia, acharacteristic obtained by mounting the large mass, driving motor offthe boom, using no counterweight for the grinding head and boom, anddriving the grinding head through an intermediate drive shaft coaxialwith the boom pivot; actuators having minimal frictionalcharacteristics, a low ratio of incremental volume to total volume, anda location such that their force is applied to the boom close to thepivotal axis thus reducing the amplitude of their motiom-and a mastercylinder for raising the grinding head from the workpiece in case of anemergency such as loss of air pressure, but connected through alost-motion connection permitting the boom to operate during grindingessentially free of the connection.

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108 9 3' K36 K152 Ill 1 I I05 0 l NO I I g PRESSURE NORM N L 1 7 SIGNAL7 PIPE ROTATING SIG NAL OPRATOR CONTROL v 144 n50 SIGNAL BILLET GRINDERAPPARATUS, PARTICULARLY FOR CONTOUR GRINDING OF PIPE BACKGROUND OF THEINVENTION This invention relates generally to a grinding machine of thekind used to remove surface defects from billets and slabs beforerolling, and more particularly to a billet grinding machine in which thegrinding wheel is applied with substantially constant force for thecontour surface grinding of a rotating round or pipe.

In the surface grinding of pipe and especially of stainless steel pipeto remove surface scale. it is considered desirable to contour grind.leaving wall thickness uniform and to leave the surface as smooth aspossible consistent with the desired rate of metal removal.

The larger horsepower machine grinders for billet grinding developedlargely from mechanization of the manually operated snag or swinggrinders in which the grinding head and driving motor were balanced on asingle frame. Typically the grinding head and driving motor of themachine grinders are mounted on the same pivotable boom. Commonly. thehead is counterweighted, and hydraulic and pneumatic actuators are usedto control the head pressure.

For a billet with an ideally straight surface, the problem of applyingthe grinding wheel with constant force is a simple one. However, forbillets that are appreciably cambered and have badly bent ends fromcropping, the work surface that the grinding wheel meets as it passesalong the billet rises and falls, sometimes at a rapid rate. The sameproblem in greater degree is presented by a pipe supported at the endson rotators. A cambered pipe is bent somewhat like a banana, andparticularly in the middle as the pipe is rotated, the surface rises andfalls with every revolution. Many pipes are not truly circular and thiseccentricity adds to the problem.

If the work surface moves upward and the grinding wheel does not, thewheel will dig into the workpiece. the effect being that greater forceis applied by the grinding wheel. Similarly if the work surface movesdownward and the grinding wheel does not follow, the workpiece will moveaway from the grinding wheel leaving a lightly ground area. This willalso cause the pipe to have a nonuniform wall thickness,

It is known in the art to sense an upward slope of the work from theincreased motor current that results, and to apply this signal tocorrect the fluid power pressure to decrease the force exerted by thewheel. It is also known in the art to use relieving valves to relievethe higher pressure built up in the boom control cylinder by theworkpiece surface moving upward against the grinding head. It isobvious, however, that by the time the current increases in the motor orthe pressure in the cylinder, that the head has already been applied tothe surface with too much force to maintain a uniform depth of cutaround the circumference of the pipe.

It was generally recognized that it is preferable to reduce friction atall bearing surfaces, and considerable work has been done in developmentof control circuits to keep the fluid power pressure in the headcylinder constant in the belief that to accomplish that goal would solvethe problem of keeping the head force constant. But this was notsufficient.

Analysis showed that more basic considerations were necessary, and itwas decided that with certain developments an open loop system mightprove more success ful than a closed loop servo system operating on thepressure. Opposing the change in the position of the grinding head arethe following forces: rotational inertia of the grinding head. itscounterweight. the boom. and the driving motor; static (coulomb)friction and stiction (starting friction) in the cylinder actuatorscaused by movement of the piston seals andv rod packing and increased bythe pressure of the oil or airi and movement of the actuator, the changein the volume causing a change in pressure at least until the relievingvalve can operate to restore the pre-set pressure. To removecounterweighting from the grinding head would introduce another problemin that in case of failure of the oil or air system pressure. the headwould drop onto the work under the full weight of the boom grindinghead.

SUMMARY OF THE INVENTION.

The grinding head and boom are not counterweighted, and the drivingmotor is mounted on the saddle which also pivotally supports the boom.Rotational inertia is thus minimized, The means for driving the pivotinggrinding wheel from the stationary drivingmotor is through anintermediate shaft mounted on the v about the pivot axis is applied by ashort moment arm.

so that the grinding head travel is approximately four times greaterthan the actuator travel. Additionally, the air bag actuators areoversized so that their ratio of incremental volume to total volume isvery small. thus the change in pressure because of actuator travel isminimized. For retracting the non-counterweighted boom with grindinghead in case of failure of the air pressure supply to the actuator, orunder other mailfunction conditions such as failure of rotation of thepipe or travel of the pipe, a master cylinder is used. The mastercylinder is connected between boom and saddle through a lost motiondevice and is supplied with air from an air storage tank. For some typesof grinding of billet contours, the degree of constant force needed canbe obtained with ordinary fluid power cylinder actuators if therotational inertia is minimized in the manner described. However, forsuccessful grinding of pipe, it has been found necessary to combine theminimizing of the actuator reactions as described above, with theminimal rotational inertia characteristics of the boom mounted grindinghead.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side elevation view taken onsection lI of the billet grinder apparatus shown as applied to grindingof pipe on a rotator car traveling beneath a stationary grinding unit,The rotator car isshown in phantom outline inasmuch as it is no part ofthe, invention. f

FIG. 2is an enlarged representation of conventional components making upthe jack screw assembly.

FIG. 3 is a top plan view of the billet grinder apparatus. Section lines1l, 44, and 55 j I ShQyvn, in this view. I

FIG. 4 is an enlarged sectional view taken on section line 44 of FIG. 3.This figure particularly shows the assembly of the boom pivot shaft intothe boom for pivoting on the saddle, and the coaxial mounting of theintermediate drive shaft.

FIG. 5 is a front elevation view taken on section line 5-5 of of FIG. 3.It particularly shows the air actuators, the boom control plate, controlrods. shock absorbers. and their mountings.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Description. FIG. 1.

In this figure the billet grinding apparatus is shown applied to thegrinding of pipe supported and rotated on a traveling car. The grindinghead can be brought into contact with the work first by bringing thewhole boom vertically within range, and then by pivoting the boom.Phantom views shows the grinding wheel at several positions. The entiregrinder unit in this application is fixed while the work is moved underit. but equally practical would be a moving grinder with a stationaryrotator. FIG. 1. shows the entire grinder unit I, mounted on a beam base2, together with the car 3 which rotates the workpiece pipe 4 and issimultaneously propelled along the rails 5 on the wheels 6 under thegrinding wheel. Inasmuch as the invention resides in the grinder unit 1,so much only of the car is exhibited as will suffice to show theconnection of the invention therewith.

Guide Shafts for the Saddle. Figs. 1, 3.

The frame 7 which is the supporting member of the grinder unit 1 is inthe form of a topless box and consists of a weldment of steel plates forsides and bottom.

Four upright shafts 8 are positioned at the four inside corners of theframe 7. Each shaft Sis turned down at the ends to a smaller diameterleaving shoulders at the transitions. The smaller diameter of each shaft8 fits into a hole 9 in the bottom of the frame 7 just large enough toreceive it, the shaft then being retained but supported on the shoulder.At the top of each shaft a shaft cap 10 with a hole just large enough tofit over the smaller diameter of the shaft at the top, bolts to frame 7,and when bolted in place bears against the shoulder of the shaft 8 andretains the shaft in place.

Jack Screw Assembly. FIGS. 1, 2.

The jack screw 11 is an assembly of conventional parts on a mountingplate 12 which is bolted to the bottom of the frame 7. The load bearingscrew 13 is driven by a worm gear unit 14 having a double shaftextension. A hydraulic motor 15 drives the worm shaft-right extension 16through a coupling 17. A rotary limit switch 18 connected to the wormshaft extension 19 through a coupling 20 is set to actuate at the limitsof travel up and down of the saddle 21. A well 22 in the base 2 allowsfor downward extension of the screw 13 when the saddle 21 is lowered.The travel of the saddle 21 is approximately forty inches vertically.The controls for the hydraulic drive motor 15 are conventional and arenot shown. However. they incorporate the limit switch 18 contacts tolimit the travel so that the operator cannot overdrive the saddle upwardor downward.

Saddle and Motor Mounting. Figs. 1, 3.

The saddle 21 is a structural weldment of brackets. mounting plates. andchannel. The saddle 21 moves vertically inside the frame 7. and isguided by the four upright shafts 8. It has at each corner accommodationfor an upper ball bushing 23 secured by a lock ring 23 and a lower ballbushing 25 secured by a lock ring 26. The entire saddle 21, guided inthis way for vertical movement. is supported on the screw 13 andconnected to it by an adaptor plate 27. Bolted on top of the motormounting sub-base 28. but separated from it by vibration mounts 29 isthe intermediate motor plate 30. The adjustable speed. dc motor 31 withdriving sheave 32 on its output shaft is enclosed and is force cooled byseparate motor driven fans in order to utilize a smaller frame size. Thefans. fan motors. conduit box. and ducting are conventional and are notshown. The adjustable speed controls for the dc motor 31 areconventional and allow the drive speed to be increased as the grindingwheel wears down to a smaller diameter. thus maintaining constantperipheral speed of the grinding surface. Such controls are well knownand are there fore not shown. The motor 31. the motor mounting plate 33,and the intermediate motor plate are bolted together, slotted holes inthe intermediate motor plate permitting the motor 31 with the motormounting plate 33 to be slidably adjustable on the intermediate motorplate 30, for tensioning the motor drive belts 86. Milled slots in themotor mounting base 28 provide clearance for the bolt heads. Theadjustment for tensioning is made by two adjustment screws 34, each ofwhich is engaged in a threaded bracket 35 of the intermediate motorplate 30. The shank end of each screw 34 is grooved and is rotatablyretained in a hole of bracket 36 on the motor mounting plate by two rollpins 37 engaging the groove above and below. Two hex nuts allow theadjustment to be secured. The motor mounting sub-base 28 is bolted tothe top of the saddle 21, slotted holes in the saddle allowing a forwardand backward adjustment of the motor mounting sub-base. The adjustmentis made by two adjustment screws 38 which have a similar function andconstruction to the two adjustment screws 34. The two adjustment screws38 permit tensioning of the spindle drive belts 85.

Boom weldment. FIG. 6.

The boom 39 is a weldment consisting of a horizontal. square tubularmember. the boom extension 40, terminating in a round tubular flange 41,a hub member 42 having a keyway 43. and an arm 44 extending rearward anddownward. Two slotted holes 45 in the arm 44 form a yoke. On the side ofthe hub 42 away from the boom extension 40, a gap 46 is cut into the hub42. Brackets 47 welded to the hub above and below the gap 46 are drilledand enable the parted back section of the hub 42 to be drawn togetherwith clamping bolt and nuts 48 for clamping purposes. Two bracket typerod clevises 49 and two drilled shock absorber brackets 50 are locatedon the boom extension 40.

Boom Pivot Assembly. FIG. 4, 6.

At the front of the saddle 21 the weldment includes two vertical sideplates 52 surmounted by a flat top bridge member 53 which form a yoke,in which the boom hub 42 is supported by pivoting of the boom 39. A boompivot shaft 54 is keyed to the boom hub 42 by key engaging keyway 43(FIG. 6) in the hub, after which the hub is clamped by clamping boltsand nuts 48. A keyway clearance groove 55 in the vertical side plates 52allows this assembly to be made. The boom pivot shaft 54 is tapered at56 to receive roller bearing 57 which are retained in place position inbearing caps 58, which in turn are bolted to the vertical side plates52. Shims 59 are used to center the boom hub 42 in this assembly. Thelock nuts 60 and lock washers 61 are used to preload the bearings froman initial clearance of approximately .008 inch to 0.004 inch. Endcovers 62 having an oval opening are bolted to the bearing caps 58. Theboom pivot shaft 54 is hollow and has oval.

openings like the bearing caps 62, the opening beings wider than high,the purpose being to allow forward and backward adjustment movement ofthe intermediate drive shaft 63 which passes through the boom pivotshaft 54, being adjusted by adjusting screws 38.

Intermediate Drive Shaft and Grinding Wheel Head Assembly. FIGS. 3,4.

The intermediate drive shaft 63 passes through the pivot boom shaft 54and is supported on two anchor bearings 64 which are bolted to the motormounting sub-base 28. On one end of the intermediate drive shaft 63 is adriven sheave 65 secured by a key 66, a lock washer 67, and a lock nut68. On the other end of the intermediate drive shaft 63 is a drivingsheave 69, secured by a key 70, a lock washer 71, and a lock nut 72. Thegrinding wheel head assembly 73 is of conventional design and no claimis made herein to any novelty associated with it. The grinding wheelhead assembly 73 is bolted to the boom flange 41 with hex head bolts 74and lock washers 75. The grinding head assembly 73 consists of thespindle 76. the sheave 77, the spindle housing 78, and means formounting the grinding wheel 79 to the spindle.

Master Cylinder. FIGS. 1,6.

The master cylinder 80 is pivotally mounted at the blind end to abracket clevis 81 of the saddle. A rod-eye 82 screwed on the end of thecylinder shaft 83 is connected to the slottedholes 45 in the arm 44 ofthe boom 39 by means of a pin 84, thus providing a lostmotion connectionbetween the cylinder shaft 83 and the arm 44 of the boom 39. With thecylinder rod 83 in its extended position, the boom can pivot downward,giving the grinding wheel a vertical movement of approximately 8 inches.

Drive Belts. FIG. 3.

A set of first belts 85 connect the spindle sheave 77 with the drivingsheave 69 of the intermediate shaft 63. A set of second belts 86connects the driven sheave 65 of the intermediate shaft 63 with themotor sheave 32.

Boom Control with Actuators. FIGS. 5,6.

The boom control plate 87 is connected to the boom extension 40 by twocontrol rods 88, having bushed holes at each end. At the upper end ofeach rod, a pin 89 connects it to a clevis bracket 49 on the boomextension 40. At the lower end of each rod 88 a pin 90 connects it to aclevis bracket 91 of the boom control plate 87. Two vertical shafts 92form guides for the boom control plate 87, ball bushings 93 being usedto minimize friction. Each shaft 92 is held in an vertical position byan upper bracket 94 and a lower bracket 95 of the saddle 21. Keeperplates 96 are used to retain the shafts in position, each keeper platefitting into a transverse groove in the upper end of each shaft. Thekeeper plates are then bolted to the upper brackets 94 An upper airactuator 97 and a lower air actuator 98 suspend the boom control plate87 between the upper actuator bracket 99 of the saddle 21 and the loweractuator bracket 100 of the saddle 21. The air actuators are commercialunits. the upper actuator 97 being a model 1T15T-1, the lower actuator98 being a model lTlSM- 2, manufactured by Firestone Industrial RubberProducts Co.. under the trademark of Airstroke. The port 101 on the topof the upper actuator 97, and a port 102 on the bottom of the loweractuator 98 are-connections for air lines. The air actuators 97, 98,have studs at top and bottom by which they are secured to the bracket99, the boom control plate 87, and bracket 100. Four mechanical stops 51on top and bottom of the boom control plate 87 limit its verticaltravel. and prevent crushing of the air actuators by over-travel. Eachof two commercial automobile type shock absorbers 103 is pivotallyconnected to a bracket 50 on the boom extension 40 at one end and at theother end is pivotally connected to a bracket 104 on the saddle 21.

Pneumatic Operation of the Master Cylinder. FIG. 6.

Air under pressure is supplied to the machine at line 105. From thefilter with automatic drain 106, air passes through line 107 to theadjustable. relieving. airline pressure regulator 108 and from therethrough line 109 to the lubricator with drain 110 and then to line 111.Air pressure passes through check valve 112 through line 113 to air tank114, through line 115 through the normally open, two-way valve 116through line 117 to the combination valve 118 which consists of a checkvalve 119 in parallel with an adjustable flow control valve 120. The airunder pressure is directed through line 121 to the rod end of cylinder80.

The cylinder rod 83 is thus retracted. the pin 84 moving to the bottomof the slotted hole 45 in the arm 44 of the boom 39 and forcing the boomextension 40 to a horizontal position. This is definedas retracting thehead.

Line 122 which is connected to the pilot port of valve 116 and to theblind end of cylinder 80 is at this time vented to atmosphere throughvalve 123.

Valve 123 consists of a two position, four way, directional, pilotoperated, spring return valve 124, piloted through internal porting 125from a three-way two position, spring return. solenoid valve 126 withsolenoid coil 127. The pressure port of valve 124 is connected thru line128 to check valve 129 which in turn is connected to line 111. Thepressure port of valve 126 is connected directly to line 111. Whensolenoid 127 is energized, the valve 126 opens, allowing pressurethrough porting 125 to operate valve 124.

This air pressure through 111, check valve 129, line Y 128 is thusapplied through valve 124, through line 122 to pilot operate valve 116to the closed position and through line 122 to the blind end of cylinder80. Simultaneously line 117 is vented to atmosphere through valve 124.Check valve 119 prevents air from the rod end of the cylinder 80 fromreturning through check valve 119 to line 117, but it can return throughflow control valve to line 117 and through valve 124 to atmosphere undercontrolled conditions. The cylinder rod 83 thus extends slowly. When itis at the end of its stroke, the boom can pivot freely within the limitsof the slotted hole 45, being controlled then by means of varying thepressure in the air actuators 97, 98. as will be explained further.

However, if at any time solenoid 127 is de-energized. the conditionsdescribed initially are present again. and the cylinder retracts fully,bringing the boom extension back into horizontal position-Also. shouldair pressure fail during grinding, so that pressure in line 111 falls toatmospheric pressure which would lose control of the boom 39 by the airactuators. check valves 112 and 129 remain checked, and the air storedin the air tank 114 operates the cylinder rod 83 to its retractedposition, again restoring the boom extension 40 back into horizontalposition. Note that even though the solenoid 127 of valve 126 mightremain energized. there is no pressure in line 111 to operate valve 124through porting 125 and hence the valve would spring return to thecondition shown in the drawing.

Pneumatic Control of the Lower Actuator. FIG. 6.

Valve consists of a two position, four way, directional, pilot operated,spring return valve 131, piloted through internal porting 132 from athree way, two position, spring return, solenoid, normally closed valve133 with solenoid 134. Line 111 is connected through valve 131 in itsspring returned position to line 139 and thus keeps line pressure onlower actuator 98, adding an upward force to the boom extension 40. Oneport of valve 131 is plugged as indicated by the When solenoid 134 isenergized, line 111 pressure is connected through valve 133 to porting132 to operate valve 131 which then connects line 139 to line 135 whichconnects to a large remotely controlled, venting regulator 136controlled by the pressure in line 137, which in turn is controlled bymanually adjustable venting regulator 138. In this condition, thepressure in the lower actuator 98 is regulated by the manual adjustmentof regulator valve 138.

Pneumatic Control of the Upper Actuator. FIG. 6.

Valve 140 consists of a two position. four way, directional, pilotoperated, spring return valve 141, piloted through internal porting 142from a three way, two position, spring return, solenoid, normally closedvalve 143 with solenoid 144. On port of valve 141 is plugged asindicated by the X. Line 149 connects to port 101 of the upper actuator97 and is normally vented to atmosphere through valve 141. Line 145 atsuch time is blocked at valve 141. When solenoid 144 is energized, line111 pressure is connected through valve 143 to porting 142 to operatevalve 141 which then connects line 149 to line 145, which in turn isconnected to a large remotely controlled venting regulator 146 controlled by the pressure in line 147 which in turn is controlled bymanually adjustable venting regulator 148. In this condition thepressure in the upper actuator 97 is regulated by manual adjustment ofregulator valve 148.

Conditions for Actuating the Master Cylinder. FIG. 7.

The derivation of an electrical signal from the rotation or movement ofa body through an appropriate sensor is well known in the art, as is thederivation of an electrical signal from the operation of an operatorscontrol switch or from the operation of a pressure switch such as 152.Similarly, it is well known how to combine such signals into circuitsthat will energize solenoids only when all such signals are present.These controls are therefore not shown, but FIG. 7 illustratesgraphically such conventional controls being used to energize solenoids127, 134, and 144, through amplifier 151. The conditions are that theair pressure is normal. the pipe is rotating and the ear is moving.combined with the signal from the operator. Should any one of thesesignals fail. the solenoids will be deenergized, and the master cylinder80 will retract the grinding wheel from the work. In this way. shouldrotation or travel of the car cease. which would ordinarily cause thewheel to grind in one spot. the wheel will be retracted from the work.Similarly. should the air pressure fail, the wheel will not drop uponthe work. but will be retracted.

Discussion of Design.

By making the boom pivot shaft of large diameter, the boom load isdistributed over multiple rollers of the roller bearings 57. Inaddition. the roller bearings 57 are preloaded to reduce their normalclearance to an operational minimum by tightening them onto the tapered56 part of the shaft 54 with the lock nuts 60. This results in a morerigid mounting of the boom and is permissible because this is not a highspeed shaft but is held for relatively slow motion. The incrementalvolume of the actuator is defined as being the difference in volume withthe actuator at one end of its permitted stroke and the volume at theother end of its permitted stroke. In a cylindrical actuator. thesmaller the ratio of incremental travel to total length of actuatorchamber. the less change such travel will make in the ratio of originalpressure to resulting pressure.

By mounting the control rods 88 of the actuator assembly so that theyact close to the pivotal axis of the boom. their travel is a fraction ofthe grinding wheel travel. The moment is considered to have a short mo-'ment arm when the actuator travel is one quarter or less of the grindingwheel travel.

When the grinding surface moves upward. the force against the wheel mustexceed the sum of ths stiction and friction of the actuator before thewheel will move. and hence cannot affect the pressure of the actuatoruntil that happens. This is the fallacy behind the attempt to controlhead force by constant pressure of the actuator. The stiction andfriction must be minimized. Conventional fluid power cylinders arecharacterized by appreciable friction and stiction. The internal sealsand packing cause such effects and the result is intensified by thepressure used. Rubber bag actuators have very low hystersis and minimalfriction and stiction characteristics. Cylinders of the rollingdiaphragm type such as Bellorfram cylinders have similarly desirablecharacteristics. In the claims the work frictional shall be construed toinclude both stiction and friction as defined earlier. The configurationof two air bags operating a suspended plate between them is conventionaland novelty is not claimed for the structure which is a double actingactuator.

Fluid power is used in the conventional sense of air or oil underpressure for the actuation of devices.

To obtain even large metal removal rates with a smooth finish, two suchbillet grinder apparatuses as described herein can be used with a singlerotater car. The first grinding wheel is set for a heavier cut, and thetrailing grinding wheel is set for the lighter grinding.

Operation.

In grinding a pipe, the rotation and travel of the car 3 are firstestablished. the drive motor 31 is adjusted to the correct speed, andthe operator brings the saddle 21 down vertically until the grindingwheel is approximately four inches from the rotating pipe. The grindingwheel has a total vertical travel of eight inches so that thisadjustment puts the wheel in the mid range of that travel. He nowactuates the control for grinding. and the master cylinder 80 extendsits rod 83. allowing the boom to be controlled by actuators 97, 98. Hethen brings the grinding wheel down onto the work by adjusting valves138 and 148. He gradually reduces the pressure from valve 138 andincreases the pressure from valve 148 until the grinding wheel is incontact with the workpiece under the desired force. The grinding shouldtake place in the mid range so that the head can respond adequately.

The invention is not to be construed as limited to the particular formsdisclosed herein. since these are to be regarded as illustrative ratherthan restrictive.

Definition of words for construction of claims. The incremental volumeof the bag actuator is defined as the difference in volume with the bagactuator at one end of its permitted stroke and the volume of the bagactuator at the other end of its permitted stroke. Permitted strokemeans simply the maximum allowable stroke or travel of the actuator asdetermined by mechanical or control means of the machine and is to bedistinguished from the working stroke which in nearly all cases will bemuch less. The moment of the boom produced by the bag actuators isconsidered to have a short moment arm when the bag actuator travel is nomore than one quarter of the corresponding travel of nation has meansfor producing relative movement of the grinding wheel along theworkpiece, and particularly the combination for contour grinding ofrounds and pipe wherein the combination also simultaneously rotates theworkpiece about its own axis, the improvement for maintaining asubstantially constant force of the wheel against a work surface thatchanges its vertical position rapidly, comprising:

a. a frame,

b. a saddle,

c. means for supporting the saddle in the frame,

d. a boom extending outwardly from the saddle,

e. a grinding wheel mounted for rotation about its central axis, on theouter end of the boom,

f. means pivotally mounting the inner end of the boom on the saddle formoving the grinding wheel onto the workpiece, thereby also establishinga piv otal axis of the boom.

g. a motor mounted on the saddle,

h. means for driving the grinding wheel from the motor,

i. an upper air bag actuator secured at its upper end to the saddle,

j. a lower air bag actuator secured at its lower end to the saddle,

k. main fluid power pressure means to control the force exerted by eachactuator for producing a differential force between them.

1. a boom control member between said actuators, secured to the lowerend of the upper actuator and to the upper end of the lower actuator soas to move between them in response to the differential force exerted bysaid actuators,

m. means for guiding the motion of said boom control member between theactuators.

n. means for limiting the travel of the boom control member.

0. means pivotally connecting said boom control member to the boom forproducing a moment of the boom about the pivotal axis of the boom.

p. emergency means having a lost motion connection to the boom. operableupon loss of pressure of main fluid power means to retract the boom forremoving the grinding wheel from the workpiece. and

q. power means for storing energy during the operation of the main fluidpower means and for supplying energy to said emergency means during lossof pressure of main fluid power means.

2. The machine defined in claim 1, wherein the means for driving thegrinding wheel from the motor includes.

a. an intermediate shaft which is substantially coaxial with the pivotalaxis of the boom.

b. a driven sheave on one end of said shaft.

c. a driving sheave on the other end of said shaft.

d. a first set of belts connecting the motor and the driven sheave.

e. a second set of belts connecting the driving sheave with the grindingwheel.

3. The machine defined in claim 2, wherein the means pivotally mountingthe inner end of the boom on the saddle includes a hollow pivotal shaft.and the intermediate shaft passes through said pivotal shaft.

4. The machine defined in claim 1, wherein the moment of the boomproduced by the bag actuators, boom control member. and connecting meanshas a short moment arm.

5. The machine defined in claim 1, wherein the bag actuators. the boomcontrol member, and the means pivotally connecting the boom controlmember to the boom are so positioned with relation to the pivotal axisof the boom that the arcuate travel of the grinding wheel axis is noless than four times the corresponding travel of the boom controlmember.

6. The machine defined in claim 1, wherein the distance between thepivotal axis of the boom and the axis I of the grinding wheel, to thedistance between said pivotal axis and the pivotal connection on theboom of the connecting means. is in the ratio of no less than four toone.

7. The machine defined in claim 1, wherein the incremental volume of theactuator to the volume of the actuator at that end of its permittedstroke when its vol ume is greatest. is in the ratio of no more than sixto ten.

8. The machine defined in claim 3, wherein the bag actuators, the boomcontrol member. and the means pivotally connecting the boom controlmember to the boom are so positioned with relation to the pivotal axisof the boom that the arcuate travel of the grinding wheel axis is noless than four times the corresponding travel of the boom controlmember.

9. The machine defined in claim 8, where in the incremental volume ofthe actuator to the volume of the actuator at that end of its permittedstroke when it volume is greatest, is in the ratioof no more than six toten.

10. In a billet grinding machine including a cooperating unit forholding the workpiece wherein the combination has means for producingrelative moment of the grinding wheel along the workpiece, andparticularly the combination for contour grinding of rounds and pipewherein the combination also simultaneously rotates the workpiece aboutits own axis. the improvement for maintaining a substantially constantforce of the wheel against a work surface that changes its verticalposition rapidly, comprising;

a. a frame,

b. a saddle,

0. means for supporting the saddle in the frame.

d. a boom extending outwardly from the saddle,

e. a grinding wheel mounted for rotation about its central axis, on theouter end of the boom,

f. means pivotally mounting the inner end of the boom on the saddle formoving the grinding wheel onto the workpiece, thereby also establishinga pivotal axis of the boom, said means including a hollow pivotal shaft,

g. a motor mounted on the saddle,

h. means for driving the grinding wheel from the motor, including anintermediate shaft which is substantially coaxial with the pivotal axisof the boom and which passes through the hollow pivotal shaft; a drivensheave on one end of said shaft; a driving sheave on the other end ofsaid shaft; a first set of belts connecting the motor and the drivensheave; and a second set of belts connecting the driving sheave with thegrinding wheel,

i. An upper air bag actuator secured at its upper end to the saddle,

j. a lower air bag actuator secured at its lower end to the saddle,

k. main fluid power pressure means to control the force exerted by eachactuator for producing a differential force between them,

l. a boom control member between said actuators. secured to the lowerend of the upper actuator and to the upper end of the lower actuator soas to move between them in response to the differential force exerted bysaid actuators,

m. means for guiding the motion of the boom control member between theactuators.

n. means for limiting the travel of the boom control member,

0. means pivotally connecting said boom control member to the boom forproducing a moment of the boom about the pivotal axis of the boom, saidbag actuators, boom control member, and pivotally connecting means beingso positioned with relation to the pivotal axis of the boom that thearcuate travel of the grinding wheel axis is no less than four times thecorresponding travel of the boom control member,

p. emergency means having a lost motion connection to the boom, operableupon loss of pressure of main fluid power means to retract the boom forremoving the grinding wheel from the workpiece, and

q. power means for storing energy during operation of the main fluidpower means and for supplying energy to said emergency means during lossof pressure of main fluid power means.

11. in a billet grinding machine including a cooperating unit forholding the workpiece wherein the combination has means for producingrelative moment of the grinding wheel along the workpiece, andparticularly the combination for contour grinding of rounds and pipewherein the combination also simultaneouslyrotates the workpiece aboutits own axis. the improvement for maintaining a substantially constantforce of the wheel against a work surface that changes its verticalposition rapidly. comprising.

a. a frame.

. a saddle.

c. means for supporting the saddle in the frame.

d. a boom extending outwardly from the saddle.

e. a grinding wheel mounted for rotation about its central axis, on theouter end of the boom,

. means pivotally mounting the inner end of the boom on the saddle sothat substantially all of the weight of the boom and grinding wheelproduces a moment of force about the pivotal axis in the same directionfor moving the grinding wheel onto the workpiece. thereby alsoestablishing a pivotal axis, said means including a hollow pivotalshaft,

g. a motor mounted on the saddle,

h. means for driving the grinding wheel from the motor, including anintermediate shaft which is substantially coaxial with the pivotal axisof the boom and which passes through the hollow pivotal shaft; a drivensheave on one end of said shaft; a driving sheave on the other end ofsaid shaft; a first set of belts connecting the motor and the drivensheave; and a second set of belts connecting the driving sheave with thegrinding wheel,

i. an upper air bag actuator secured at its upper end to the saddle.

j. a lower air bag actuator secured at its lower end to the saddle.

k. main fluid power pressure means to control the force exerted by eachactuator for producing a differential force between them,

1. a boom control member between said actuators, secured to the lowerend of the upper actuator and to the upper end of the lower actuator soas to move between them in response to the differential force exerted bysaid actuators,

m. means for guiding the motion of the boom control member between theactuators,

n. means for limiting the travel of the boom control member, and

0. means pivotally connecting said boom control member to the boom forproducing a moment of the boom about the pivotal axis of the boom, saidbag actuators, boom control member, and pivotally connecting means beingso positioned with relation to the pivotal axis of the boom that thearcuate travel of the grinding wheel axis is no less than four times thecorresponding travel of the boom control member.

12. In a billet grinding machine including a cooperating unit forholding the workpiece wherein the combination has means for producingrelative movement of the grinding wheel along the workpiece, andparticularly the combination for contour grinding of rounds and pipewherein the combination also simultaneously rotates the workpiece aboutits own axis, the improvement for maintaining a substantially constantforce of the wheel against a work surface that changes its verticalposition rapidly, comprising:

a. a frame, b. a saddle, c. means for supporting the saddle in theframe,

d. a boom extending outwardly from the saddle.

e. a grinding wheel mounted for rotation about its central axis, on theouter end of the boom.

f. means pivotally mounting the inner end of the boom on the saddle sothat substantially all of the weight of the boom and grinding wheelproduces a moment of force about the pivotal axis in the same directionfor moving the grinding wheel onto the workpiece, thereby alsoestablishing a pivotal axis. said means including a hollow pivotalshaft.

g. a motor mounted on the saddle.

h. means for driving the grinding wheel from the motor.

i. an upper air bag actuator secured at its upper end to the saddle,

j. a lower air bag actuator secured at its lower end to the saddle,

k. main fluid power pressure means to control the force exerted by eachactuator for producing a dif-.

0. means pivotally connecting said boom control member to the boom forproducing a moment of the boom about the pivotal axis of the boom.

1. In a billet grinding machine including a cooperating unit for holdingthe workpiece wherein the combination has means for producing relativemovement of the grinding wheel along the workpiece, and particularly thecombination for contour grinding of rounds and pipe wherein thecombination also simultaneously rotates the workpiece about its ownaxis, the improvement for maintaining a substantially constant force ofthe wheel against a work surface that changes its vertical positionrapidly, comprising: a. a frame, b. a saddle, c. means for supportingthe saddle in the frame, d. a boom extending outwardly from the saddle,e. a grinding wheel mounted for rotation about its central axis, on theouter end of the boom, f. means pivotally mounting the inner end of theboom on the saddle for moving the grinding wheel onto the workpiece,thereby also establishing a pivotal axis of the boom, g. a motor mountedon the saddle, h. means for driving the grinding wheel from the motor,i. an upper air bag actuator secured at its upper end to the saddle, j.a lower air bag actuator secured at its lower end to the saddle, k. mainfluid power pressure means to control the force exerted by each actuatorfor producing a differential force between them, l. a boom controlmember between said actuators, secured to the lower end of the upperactuator and to the upper end of the lower actuator so as to movebetween them in response to the differential force exerted by saidactuators, m. means for guiding the motion of said boom control memberbetween the actuators, n. means for limiting the travel of the boomcontrol member, o. means pivotally connecting said boom control memberto the boom for producing a moment of the boom about the pivotal axis ofthe boom, p. emergency means having a lost motion connection to theboom, operable upon loss of pressure of main fluid power means toretract the boom for removing the grinding wheel from the workpiece, andq. power means for storing energy during the operation of the main fluidpower means and for supplying energy to said emergency means during lossof pressure of main fluid power means.
 2. The machine defined in claim1, wherein the means for driving the grinding wheel from the motorincludes, a. an intermediate shaft which is substantially coaxial withthe pivotal axis of the boom, b. a driven sheave on one end of saidshaft, c. a driving sheave on the other end of said shaft, d. a firstset of belts connecting the motor and the driven sheave, e. a second setof belts connecting the driving sheave with the grinding wheel.
 3. Themachine defined in claim 2, wherein the means pivotally mounting theinner end of the boom on the saddle includes a hollow pivotal shaft, andthe intermediate shaft passes through said pivotal shaft.
 4. The machinedefined in claim 1, wherein the moment of the boom produced by the bagactuators, boom control member, and connecting means has a short momentarm.
 5. The machine defined in claim 1, wherein the bag actuators, theboom control member, and the means pivotally connecting the boom controlmember to the boom are so positioned with relation to the pivotal axisof the boom that the arcuate travel of the grinding wheel axis is noless than four times the corresponding travel of the boom controlmember.
 6. The machine defined in claim 1, wherein the distance betweenthe pivotal axis of the boom and the axis of the grinding wheel, to thedistance between said pivotal axis and the pivotal connection on theboom of the connecting means, is in the ratio of no less than four toone.
 7. The machine defined in claim 1, wherein the incremental volumeof the actuator to the volume of the actuator at that end of itspermitted stroke when its volume is greatest, is in the ratio of no morethan six to ten.
 8. The machine defined in claim 3, wherein the bagactuators, the boom control member, and the means pivotally connectingthe boom control member to the boom are so positioned with relation tothe pivotal axis of the boom that the arcuate travel of the grindingwheel axis is no less than four times the corresponding travel of theboom control member.
 9. The machine defined in claim 8, where in theincremental volume of the actuator to the volume of the actuator at thatend of its permitted stroke when it volume is greatest, is in the ratioof no more than six to ten.
 10. In a billet grinding machine including acooperating unit for holding the workpiece wherein the combination hasmeans for producing relative moment of the grinding wheel along theworkpiece, and particularly the combination for contour grinding ofrounds and pipe wherein the combination also simultaneously rotates theworkpiece about its own axis, the improvement for maintaining asubstantially constant force of the wheel against a work surface thatchanges its vertical position rapidly, comprising; a. a frame, b. asaddle, c. means for supporting the saddle in the frame, d. a boomextending outwardly from the saddle, e. a grinding wheel mounted forrotation about its central axis, on the outer end of the boom, f. meanspivotally mounting the inner end of the boom on thE saddle for movingthe grinding wheel onto the workpiece, thereby also establishing apivotal axis of the boom, said means including a hollow pivotal shaft,g. a motor mounted on the saddle, h. means for driving the grindingwheel from the motor, including an intermediate shaft which issubstantially coaxial with the pivotal axis of the boom and which passesthrough the hollow pivotal shaft; a driven sheave on one end of saidshaft; a driving sheave on the other end of said shaft; a first set ofbelts connecting the motor and the driven sheave; and a second set ofbelts connecting the driving sheave with the grinding wheel, i. An upperair bag actuator secured at its upper end to the saddle, j. a lower airbag actuator secured at its lower end to the saddle, k. main fluid powerpressure means to control the force exerted by each actuator forproducing a differential force between them, l. a boom control memberbetween said actuators, secured to the lower end of the upper actuatorand to the upper end of the lower actuator so as to move between them inresponse to the differential force exerted by said actuators, m. meansfor guiding the motion of the boom control member between the actuators,n. means for limiting the travel of the boom control member, o. meanspivotally connecting said boom control member to the boom for producinga moment of the boom about the pivotal axis of the boom, said bagactuators, boom control member, and pivotally connecting means being sopositioned with relation to the pivotal axis of the boom that thearcuate travel of the grinding wheel axis is no less than four times thecorresponding travel of the boom control member, p. emergency meanshaving a lost motion connection to the boom, operable upon loss ofpressure of main fluid power means to retract the boom for removing thegrinding wheel from the workpiece, and q. power means for storing energyduring operation of the main fluid power means and for supplying energyto said emergency means during loss of pressure of main fluid powermeans.
 11. In a billet grinding machine including a cooperating unit forholding the workpiece wherein the combination has means for producingrelative moment of the grinding wheel along the workpiece, andparticularly the combination for contour grinding of rounds and pipewherein the combination also simultaneously rotates the workpiece aboutits own axis, the improvement for maintaining a substantially constantforce of the wheel against a work surface that changes its verticalposition rapidly, comprising; a. a frame, b. a saddle, c. means forsupporting the saddle in the frame, d. a boom extending outwardly fromthe saddle, e. a grinding wheel mounted for rotation about its centralaxis, on the outer end of the boom, f. means pivotally mounting theinner end of the boom on the saddle so that substantially all of theweight of the boom and grinding wheel produces a moment of force aboutthe pivotal axis in the same direction for moving the grinding wheelonto the workpiece, thereby also establishing a pivotal axis, said meansincluding a hollow pivotal shaft, g. a motor mounted on the saddle, h.means for driving the grinding wheel from the motor, including anintermediate shaft which is substantially coaxial with the pivotal axisof the boom and which passes through the hollow pivotal shaft; a drivensheave on one end of said shaft; a driving sheave on the other end ofsaid shaft; a first set of belts connecting the motor and the drivensheave; and a second set of belts connecting the driving sheave with thegrinding wheel, i. an upper air bag actuator secured at its upper end tothe saddle, j. a lower air bag actuator secured at its lower end to thesaddle, k. main fluid power pressure means to control the force exertedby each actuator for producing a differential force between them, l. aboom control member between said actuators, secureD to the lower end ofthe upper actuator and to the upper end of the lower actuator so as tomove between them in response to the differential force exerted by saidactuators, m. means for guiding the motion of the boom control memberbetween the actuators, n. means for limiting the travel of the boomcontrol member, and o. means pivotally connecting said boom controlmember to the boom for producing a moment of the boom about the pivotalaxis of the boom, said bag actuators, boom control member, and pivotallyconnecting means being so positioned with relation to the pivotal axisof the boom that the arcuate travel of the grinding wheel axis is noless than four times the corresponding travel of the boom controlmember.
 12. In a billet grinding machine including a cooperating unitfor holding the workpiece wherein the combination has means forproducing relative movement of the grinding wheel along the workpiece,and particularly the combination for contour grinding of rounds and pipewherein the combination also simultaneously rotates the workpiece aboutits own axis, the improvement for maintaining a substantially constantforce of the wheel against a work surface that changes its verticalposition rapidly, comprising: a. a frame, b. a saddle, c. means forsupporting the saddle in the frame, d. a boom extending outwardly fromthe saddle, e. a grinding wheel mounted for rotation about its centralaxis, on the outer end of the boom, f. means pivotally mounting theinner end of the boom on the saddle so that substantially all of theweight of the boom and grinding wheel produces a moment of force aboutthe pivotal axis in the same direction for moving the grinding wheelonto the workpiece, thereby also establishing a pivotal axis, said meansincluding a hollow pivotal shaft, g. a motor mounted on the saddle, h.means for driving the grinding wheel from the motor, i. an upper air bagactuator secured at its upper end to the saddle, j. a lower air bagactuator secured at its lower end to the saddle, k. main fluid powerpressure means to control the force exerted by each actuator forproducing a differential force between them, l. a boom control memberbetween said actuators, secured to the lower end of the upper actuatorand to the upper end of the lower actuator so as to move between them inresponse to the differential force exerted by said actuators, m. meansfor guiding the motion of said boom control member between theactuators, n. means for limiting the travel of the boom control member,and o. means pivotally connecting said boom control member to the boomfor producing a moment of the boom about the pivotal axis of the boom.